POSTN and asthma: Compared with cluster 3, cluster 4 showed a high serum periostin level (87.1 ± 32.3 vs. 66.5 ± 21.8 ng/mL, p = 0.05) and a higher prevalence of the comorbidities: DM (p < 0.01), albuminuria (p < 0.01), hypertension (p = 0.03), and asthma (p = 0.01).